Field of the Invention
The present invention relates to a liquid crystal display device, and more particularly, to a liquid crystal display device which ensures the holding power of a double-sided tape by minimizing the size of a guide panel and extending the double-sided tape to the bottom of a light guide plate.
Description of the Related Art
Recently, with the development of various portable electronic devices, such as mobile phones, personal digital assistances (PDA's), and laptop computers, the demand for a light-weight, thin, short and small flat panel display device that may be applied to various portable electronic devices has been increasing. As such, flat panel display devices, such as liquid crystal displays (LCDs), plasma display panels (PDPs), field emission displays (FEDs), vacuum fluorescent displays (VFDs), and the like have been actively studied. Among them, the LCDs have received much attention due to the possibility of mass production, the ease in driving such a device, its high picture quality, and the ability to produce a large-size screen.
The LCD is a transmissive display device that displays a desired image on a screen by adjusting the amount of light transmitting through a liquid crystal layer according to a refractive index anisotropy of liquid crystal molecules. Thus, the LCD includes a backlight, which is a light source that provides light transmitted through the liquid crystal layer to display an image. In general, the backlight is divided into two types: a side type backlight in which lamps or other light sources are installed at the side of a liquid crystal display panel and provide light to the liquid crystal layer; and a direct type backlight in which lamps or other light sources provide light directly from a lower portion of a liquid crystal display panel.
The side type backlight is installed at the side of the liquid crystal display panel to provide light to the liquid crystal layer via a reflective plate and a light guide plate. Thus, because the side type backlight can contribute to reduce the thickness, it is largely used for a laptop computer, etc. that requires a thin display device. However, the lamps for emitting light of the side type backlight are positioned at the side of the liquid crystal display panel, the side type backlight is not applicable to a large liquid crystal display panel and, in addition, because light is supplied through the light guide plate, high luminance cannot be obtained. Thus, the side type backlight is not suitable for a liquid crystal display panel in use for a large-scale LCD TV which has been recently drawing much attention.
As for the direct type backlight, because light emitted from the lamps is directly supplied to the liquid crystal layer, the direct type backlight is applicable to a large liquid crystal display panel. In addition, the direct type backlight has high luminance, it can be largely used in fabricating a liquid crystal display panel for an LCD TV.
FIG. 1 is a view showing a liquid crystal display device with a backlight according to a related art.
As shown in FIG. 1, the liquid crystal display device according to the related art includes a liquid crystal display panel 10 including a first substrate 1, a second substrate 2, and a liquid crystal layer (not shown) interposed between the first and second substrates and implementing an image upon application of a signal from an external source; a light guide plate 35 disposed below the liquid crystal display panel 10 and guiding light emitted from a light source (not shown) to supply the light to the liquid crystal display panel 10; an optical sheet 38 provided between the liquid crystal display panel 10 and the light guide plate 35 and including a diffusion sheet 38a and prism sheets 38b and 38c for diffusing and condensing light guided by the light guide plate 35 to supply the light to the liquid crystal display panel 10; a reflective plate 36 disposed under the light guide plate 35 and reflecting the light guided down the light guide plate 35; a bottom cover 40 accommodating the reflective plate 36, the light guide plate 35, and the optical sheet 38; a guide panel 42 coupled with the bottom cover 40 to assemble the reflective plate 36, the light guide plate 35, and the optical sheet 38 and having the liquid crystal display panel 10 located on top of it; and a top cover 46 coupled with the guide panel 42 to assemble the liquid crystal display panel 10.
The first substrate 1 of the liquid crystal display panel 10 is a thin film transistor array substrate where thin film transistors are formed. Various lines and pixel electrodes, as well as the thin film transistors, are formed on the first substrate 1. The second substrate 2 is a color filter substrate where color filter layers and a black matrix are formed. A first polarizer 3 and a second polarizer 4 are respectively attached to the first and second substrates 1 and 2 of the liquid crystal display panel 10 to change the polarization state of light coming into and going out of the liquid crystal display panel 10 and implement an image.
When assembling the liquid crystal display panel 10, the top cover 46 and the guide panel 42 are coupled by a coupling unit such as screws, the guide panel 42 is attached to the reflective plate 36 disposed under a double-sided tape 32, and the liquid crystal display panel 10 is held and assembled by the guide panel 46.
However, the liquid crystal display device having such a structure has the following problems.
In recent years, much attention has been being given to liquid crystal display devices with attractive appearance which become smaller in size and as lightweight as possible by minimizing the bezel area. To fabricate a liquid crystal display device with a minimized bezel, it is necessary to make the outer edge region of the liquid crystal display device occupied by the guide panel 46 by minimizing the size of the guide panel, which is disposed on the outer edge of the liquid crystal display device, holds the liquid crystal display panel 10, and is coupled with the bottom cover and the top cover.
By the way, the width of the double-sided tape 32, adhering to the guide panel 46 to attach and fix the guide panel 46 and the reflective plate 36, should be reduced when minimizing the size of the guide panel 46. However, the size of the guide panel 34, to which the double-sided tape adheres, that is, which is formed along the outer periphery of the liquid crystal display panel 10, also increases as the liquid crystal display device becomes larger and the size of the liquid crystal display panel increases. Hence, the length of the double-sided tape 32 adhering to the guide panel 46 in a strip shape increases. On the other hand, as the width of the double-sided tape 32 decreases, the double-sided tape 32 should be cut lengthwise into narrow strips. As a result, the cutting precision is lowered.
That is to say, it takes a long processing time to form narrow strips of double-sided tape 32, and high-precision processing equipment is required, thus raising the manufacturing costs.